This invention relates to an improvement in vehicular automatic speed change gear assemblies.
A conventional automatic speed change gear assembly is designed so that an oil pressure control circuit thereof includes a manual valve having the six positions P, R, N, D, 2 and L to permit the speed change gear mechanism to provide a plurality of speed ranges. Accordingly, the coventional automatic speed change gear assembly is disadvantageous in the following points: It is necessary to provide a large space in the vehicle in order to provide the above-described operating lever. Furthermore, the operator may operate the operating lever erroneously. More specifically, the manual valve may be set to the position P for parking the vehicle or to the position R for running the vehicle in reverse while the vehicle is moving forwardly, or the manual valve may be switched to the position N in returning it to position D from either second or low.
Furthermore, in order to park the vehicle, it is necessary to shift the operating lever to a position corresponding to the position P of the manual valve. Accordingly, the conventional automatic speed change gear assembly suffers from difficulties in that it is troublesome to shift the operating lever to the P position whenever it is required to park the vehicle, and if the operator forgets to so set the operating lever in parking the vehicle on a slope, a hazard occurs in that the vehicle may roll unintentionally.